Discharging device for electric furnaces



sept. 16', 1924. 1,509,001

C. T. THORSSELL ET AL DISCHARGING DEVICE FOR ELECTRIC FURNAGES Filed JuneA 20. 1921 ETC.- araseJZ Patented Sept. 16, 1924.

UNITED STATES PATENT OFFICE.

CARI.. THEODOR THORSSELL AND ERBE CHRISTAN BECK-FE11S, 0F GOTTENBORG,

' SWEDEN.

DISCHARGING DEVICE FOIR. ELECTRIC FURNACES.

Application filed .Tune 20, 1921. Serial No. 479,042.

To all whom t may concern.'

Be it known that we, CARLv THnoDoP. THoRssnLL and EBEE CHRISTIAN Buon-Faris, subjects of the King of Sweden, residing'at Gottenborg, in the Kingdom of Sweden, have invent-ed certain new and useful Improvements of Discharging Devices for Electric Furnaces.

This invention relates to such electric shaft furnaces in which the material in the furnace is discharged by means of a grate or the like. If in such electric furnaces the heating is brought about on account of the material to be treated being conductive itself, and if the discharging grate consists of conductive material the disadvantage will arise that the electric current, instead of passing through the massto be heated, finds its way to the grate and follows the same between the electrodes. Except a loss of energy the inconvenience is hereby brought about that the parts in the neighbourhood of the grate will be heated instead of the material placed directly vbetween the electrodes of the furnace, and whereby, of course, partly the progress of work in the furnace is disturbed and partly the grate will be destroyed.

According to the invention such grates are arranged in such a manner that the inconveniences stated above are eliminated and this is done by placing the grate in such a way in relation to the electrodes of the furnace or by constructing the grate so that its tendency to conduct the electric current will be about nulliiied. This may in the first place be brought about by placing the parallel elements of the grate perpendicularly to the direction of the current lines between the electrodes of the furnace in such a way that they will have as little iniiuence as possible on the straight current lines passing through the mass to be heated. Besides, t-he different elements ofthe grate may also be insulated from each other.

In spite of the measures thus taken it might happen that the current passes through one grate element and then, without passing through the intermediate mass, through the construction carrying the grate to the next grate element. Hereby the grate is exposed to an injurious heating and besides a great quantity of heat is lost instead of being used for heating the material to be treated in the furnace. This inconvenience may be eliminated by separating the ends of each grate element from the part of the elementbeing in contact with the mass to be treated by means of a suitable insulating material. The construction carrying the grate may also be divided in several parts or sections electrically insulated from each other..V Hereby the advantage is obtained that the potential difference between two such parts or sections adjacent. to each other will be essentially smaller than the potential difference between the ends of the construction carrying the grate elements, whereby also the current, which otherwise would pass through the grate and thus be drawn away Vfrom the material to be heated, will be substantially reduced. For the same purpose the frame or the construction carrying the grate bars may also be made of non-conducting material, such as cement, stone or the like.

In such cases when the grate elements are made to turn for the purpose of discharging the material treated in the furnace, the bear` ings of the grate bars may be insulated from the carrying parts for obtaining the same result.

A form of the invention is shown in the accompanying drawing. Fig. l shows in vertical section a discharging grate having rotatory grate bars and Fig. 2 is a plan view of the same. Fig. 3 shows the connection between one end of a grate bar and the carrying device.

According to the drawing the grate consists of a number of grate bars l parallel with each other and at their ends journaled in the supports 2. The grate bars are provided with projections or the like for facilitating the movement of the material passing through the furnace shaft after having passed between two electrodes placed opposite each other at the heating Zone in the furnace walls. In order to get the material to be treated uniformly heated it is necesn sary, as above stated, that the current between the electrodes passes uniformly through the material in evenly distributed, straight current lines without having any tendency to deviate downwards through the grate when the latter is made of a material that is more conductive than the material to be treated. For this purpose the grate bars l are placed in such a way that they are insulated from each other and lie per- *Y Y i "1,509,002V

Y andrco'n'sisting of apluralty of parts lvvliicliV Y pendicularly Vto a vertical plane through the t-Wo electrodes. Y

The grate bars may also near their ends by means of a suitable insulating materialV they may beVV insulated from thesupport,V

as shown in Fig. v3. Here the bearing 5`car- VryingV the journal of the grate bar is sepa rated from the support 2 by means of an inwhich also surrounds the sulting layer 6 1 boltsfT, by means of VWhich the bearingV is :fastened to the support, and extends' under the Washers 8. j

What We claim is 1 '1I In electrically heated furnaces for heating electrically conductive Vmaterial a' grate-shape device carrying Ysaid material are'electrically insulated from each other.

2. In electrically heated furnaces for heat-V ing electrically conductive material a grate- Vshaped device carrying said material and consisting'of a plurality otparallel mem# bers, each of which members is divided two insulating layers in such a Way that vthe ends of such member are electrically in-V sulated from the part of the member lbeing in contact With the mass to beV treated in Y the furnace.

' 3. lnV electrically heated furnaces for heating electrically conductive material a grate-A I shaped device carrying said material and consisting of a plurality of parallel mein-V bers resting with their ends in bearings, that are electrically insulated. from the parts supporting the same.

Il. ln electrically heated furnaces for heat ing electrically conductive Vmaterial a grateshape device VcarryingV said material and consisting ofV a plurality of parallel inem-V bers carried by a support divided in a number of sections insulated from each other.

In testimonyWhereoiwe have signed our names to this specication in the presencek of tWo subscribing Witnesses.

oiiL'frHEonoR TiioiissiiLL.

Witnesses;

ERBUR M. ANDERSON, VALFRID Jonsson. Y 

